The present invention relates to a coil unit relating to non-contact power transmission using a coil, an electronic instrument, and the like.
Non-contact power transmission which utilizes electromagnetic induction to enable power transmission without metal-to-metal contact has been known. As application examples of non-contact power transmission, charging a portable telephone, a household appliance (e.g., telephone handset), and the like has been proposed.
In power transmission utilizing electromagnetic induction, the amount of deviation of a coil from the coaxial line affects the amount of power transmission to a large extent. Therefore, it is important that a charging target be placed at an appropriate position of a charger. The following technologies have been proposed in order to appropriately position the charging target with respect to the charger.
JP-A-6-311659 discloses technology which prevents insertion of a foreign object between a charging target and a charger so that charging occurs at an appropriate position.
JP-A-7-322534 discloses electromagnetic coupling technology in which a protruding core is inserted into an air-core solenoid coil.
JP-A-6-303726 discloses technology which produces primary/secondary electromagnetic coupling by inserting a primary-side core into an air-core section of a secondary-side coil.
In the above technologies, the core is provided in the coil.